The Church of St Mary the Less, in Old Bury Road, Thetford, has been not been used since 1975. Its ownership has changed several times, while the building deteriorated. A large section of roof over the north aisle collapsed just before Christmas.
The local council has now issued an urgent works notice to force the repairs to be done by the owner of the building, London-based retired company director Ron Collins.
Mr Collins will be given 14 days to do the work, and if he refuses the council can have the work carried out and then claim the money from him by seizing his personal assets.
English Heritage has indicated it would grant four-fifths of unrecoverable costs up to a maximum of £30,000.
Council leader William Nunn said it was essential for a strong message to be sent to all owners of at-risk buildings. He told a local paper: “I hope that by pursuing him personally for his liabilities it will lead him to take his respon-sibilities seriously. If people are buying up old buildings and trying to make a quick buck, we will make sure they do them up and preserve them or sell them on to someone who will do that.”
St Mary the Less is one of only three surviving medieval churches in Thetford. The church also needs protection to stop pigeons getting in, works to the tower roof and regular monitoring of its security.
Breckland deputy leader Bill Smith said: “I deplore the current state of the building. The owners really need to look at themselves and ensure the work is carried out. It is quite bad that they are not fulfilling their obligations to carry out their responsibilities. The work must be carried out."
Ownership of the building has changed several times in recent years, and previous permission granted to turn the church into flats has lapsed.
Mr Collins bought the building in 2004 for £124,000 and is offering the building on the open market for £199,950.
He said any damage to the building was not a result of deterioration but of vandalism, and added that he did not have the money to fix the damage.
“People throw things through the roof, and we've been down many times and locked it up, but they just use diamond cutters to get through,” he said. “At the time [of purchase] it had planning permission, but the vandalism has been so great. It wasn't worth spending the money to do the works to the building. Until it's converted into a livable building there's no hope of stopping it.”